This invention relates generally to space temperature conditioning systems and in particular to a new and improved method of determining acceptability of a selected condition in a space temperature conditioning system.
Space temperature conditioning systems of the type having a refrigerant as a heat transfer medium are well-known in the art. It is important that the system have sufficient charge of refrigerant in order to function properly. Therefore, it is advisable to monitor the refrigerant charge level in the system to determine if the charge level is acceptable.
Various methods of determining refrigerant charge level are known in the art. One type of method involves steady-state measurements of a selected system operating parameter, such as the subcooling temperature at the condenser outlet, as exemplified by U.S. Pat. No. 5,987,903. Disadvantages of such xe2x80x9csteady statexe2x80x9d methods of determining refrigerant charge level are that the system must operate at a steady state condition and that the measurements are sensitive to outdoor and indoor ambient temperatures.
Another type of method of determining refrigerant charge level involves measurements of changes in a system operating parameter under transient conditions, as exemplified by U.S. Pat. No. 5,152,152. A disadvantage of such prior art xe2x80x9ctransientxe2x80x9d methods is that they usually require relatively expensive components, such as pressure sensors and/or valves, to perform the necessary measurements.
There is, therefore, a need for an improved method of determining the acceptability of a selected condition, such as refrigerant charge level, in a space temperature conditioning system. There is also a need for a method of determining acceptability of refrigerant charge level in a space temperature conditioning system that is both relatively inexpensive and reliable under a wide range of ambient temperature conditions.